Hollingworthite is a rare platinum-group mineral typically occurring as microscopic inclusions within other platinum-group alloys or sulfide ores. Collectors rarely encounter it as hand specimens, as it is usually found via micro-analysis of ore samples from large igneous complexes.
Is this hollingworthite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch hollingworthite with a known reference. Hollingworthite sits at Mohs 6, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Hollingworthite leaves a grayish-black streak.
- 3Read the lusterHold the specimen under a strong light. Hollingworthite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: silver-white, light-gray.
- 5Look at form & habitCrystal system: cubic. Typical habit: anhedral grains, inclusions in platinum-group minerals.
Often confused with
Hollingworthite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Hollingworthite leaves grayish-black, Cobaltite leaves greyish-black.
How to tell apart: Streak differs, so Hollingworthite leaves grayish-black, Sperrylite leaves black.
Often found alongside hollingworthite
Minerals reported to co-occur with hollingworthite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Rh,Pt,Pd)AsS
- Mohs hardness
- 6
- Density
- 9.5-10.0 g/cm³
- Colors
- Streak
- Grayish-black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Anhedral Grains, Inclusions in Platinum-group Minerals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Scientific Study
- Host rock
- Mafic and Ultramafic Igneous Rocks
- Typical price
- $50-500 depending on specimen size and purity
Where rockhounds find hollingworthite
Classic worldwide localities
- Bushveld Complex, South Africa
- Stillwater Complex, USA
- Norilsk, Russia
- Sudbury, Canada
Field-hunting tip
Look in mafic and ultramafic igneous rocks country, the host setting where hollingworthite typically forms. If you start seeing platinum, palladium, sperrylite in float, you are in the right ground. Field specimens usually show a anhedral grains, inclusions in platinum-group minerals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify hollingworthite?+
Where is hollingworthite found?+
How much is hollingworthite worth?+
Is hollingworthite safe to handle?+
What rocks look like hollingworthite?+
What minerals are found with hollingworthite?+
What kind of rock does hollingworthite form in?+
What is hollingworthite used for?+
Find hollingworthite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
